1. Field of Technology
The present invention relates to a paper discharge mechanism for a printer that prevents recording paper discharged by a discharge roller from being pulled back into the printer by the discharge roller, and relates more particularly to a printer paper discharge mechanism that is suitable for use in a roll paper printer arranged to print on roll paper and then cut and discharge the printed paper.
2. Description of Related Art
Roll paper printers typically have a paper cutting mechanism and a discharge roller disposed downstream from the printing position where the print head is located. After printing, the printed paper tape is then cut to a certain length, and the cut length of paper is then discharged by the discharge roller. After discharging the paper, the paper tape is wound back inside the printer in order to position the leading end of the paper for the next printing operation. Roll paper printers having this type of paper cutting mechanism are taught, for example, in Japanese Unexamined Patent Appl. Pub. 2002-346976 and Japanese Unexamined Patent Appl. Pub. 2003-118187.
To assure that the cut off end of the recording paper is completely discharged from the printer, the paper discharge operation continues until the trailing end of the cut paper passes the discharge roller. As a result, the leading end of the paper roll left after cutting off the printed end also extends a specific distance on the discharge side of the nipping portion of the discharge roller. If multiple discharged slips have accumulated in the discharge area, or if the paper is discharged at an angle, the leading end of the roll paper delivered downstream from the discharge roller may be inserted below one or more pieces of discharged paper. This can result in the discharged paper resting on top of the exposed leading end of the roll paper coming with the leading end of the paper tape when the paper is then pulled back inside the paper transportation path, resulting in the discharged paper being nipped and pulled by the discharge roller back into the transportation path. The discharged paper may thus be pulled by the reversing discharge roller back inside the printer when the roll paper is reversed for repositioning for the next printing operation.
Furthermore, thus pulling discharged paper back inside the printer can cause a paper jam.
While sensors can be used to detect the leading end of the paper tape that is pulled back into the printer, the sensor is unable to find the leading edge if the leading edge of the paper is overlapped by the discharged paper that is also pulled back inside. The leading end of the paper therefore cannot be correctly positioned for the next printing operation.